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<a href="util_8cpp.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a id="l00001" name="l00001"></a><span class="lineno">    1</span><span class="comment">/* Flow</span></div>
<div class="line"><a id="l00002" name="l00002"></a><span class="lineno">    2</span><span class="comment"> * Copyright 2023 Akamai Technologies, Inc.</span></div>
<div class="line"><a id="l00003" name="l00003"></a><span class="lineno">    3</span><span class="comment"> *</span></div>
<div class="line"><a id="l00004" name="l00004"></a><span class="lineno">    4</span><span class="comment"> * Licensed under the Apache License, Version 2.0 (the</span></div>
<div class="line"><a id="l00005" name="l00005"></a><span class="lineno">    5</span><span class="comment"> * &quot;License&quot;); you may not use this file except in</span></div>
<div class="line"><a id="l00006" name="l00006"></a><span class="lineno">    6</span><span class="comment"> * compliance with the License.  You may obtain a copy</span></div>
<div class="line"><a id="l00007" name="l00007"></a><span class="lineno">    7</span><span class="comment"> * of the License at</span></div>
<div class="line"><a id="l00008" name="l00008"></a><span class="lineno">    8</span><span class="comment"> *</span></div>
<div class="line"><a id="l00009" name="l00009"></a><span class="lineno">    9</span><span class="comment"> *   https://www.apache.org/licenses/LICENSE-2.0</span></div>
<div class="line"><a id="l00010" name="l00010"></a><span class="lineno">   10</span><span class="comment"> *</span></div>
<div class="line"><a id="l00011" name="l00011"></a><span class="lineno">   11</span><span class="comment"> * Unless required by applicable law or agreed to in</span></div>
<div class="line"><a id="l00012" name="l00012"></a><span class="lineno">   12</span><span class="comment"> * writing, software distributed under the License is</span></div>
<div class="line"><a id="l00013" name="l00013"></a><span class="lineno">   13</span><span class="comment"> * distributed on an &quot;AS IS&quot; BASIS, WITHOUT WARRANTIES OR</span></div>
<div class="line"><a id="l00014" name="l00014"></a><span class="lineno">   14</span><span class="comment"> * CONDITIONS OF ANY KIND, either express or implied.</span></div>
<div class="line"><a id="l00015" name="l00015"></a><span class="lineno">   15</span><span class="comment"> * See the License for the specific language governing</span></div>
<div class="line"><a id="l00016" name="l00016"></a><span class="lineno">   16</span><span class="comment"> * permissions and limitations under the License. */</span></div>
<div class="line"><a id="l00017" name="l00017"></a><span class="lineno">   17</span><span class="comment"></span> </div>
<div class="line"><a id="l00018" name="l00018"></a><span class="lineno">   18</span><span class="comment">/// @file</span></div>
<div class="line"><a id="l00019" name="l00019"></a><span class="lineno">   19</span><span class="comment"></span><span class="preprocessor">#include &quot;<a class="code" href="util_2util_8hpp.html">flow/util/util.hpp</a>&quot;</span></div>
<div class="line"><a id="l00020" name="l00020"></a><span class="lineno">   20</span> </div>
<div class="line"><a id="l00021" name="l00021"></a><span class="lineno">   21</span><span class="keyword">namespace </span><a class="code hl_namespace" href="namespaceflow_1_1util.html">flow::util</a></div>
<div class="line"><a id="l00022" name="l00022"></a><span class="lineno">   22</span>{</div>
<div class="line"><a id="l00023" name="l00023"></a><span class="lineno">   23</span> </div>
<div class="line"><a id="l00024" name="l00024"></a><span class="lineno">   24</span><span class="comment">// Types.</span></div>
<div class="line"><a id="l00025" name="l00025"></a><span class="lineno">   25</span><span class="comment"></span> </div>
<div class="line"><a id="l00026" name="l00026"></a><span class="lineno">   26</span><span class="comment">/**</span></div>
<div class="line"><a id="l00027" name="l00027"></a><span class="lineno">   27</span><span class="comment"> * Internally used class that enables some of the activities of beautify_chrono_ostream() API.  It&#39;s a locale facet,</span></div>
<div class="line"><a id="l00028" name="l00028"></a><span class="lineno">   28</span><span class="comment"> * whose `virtual` API can be used to imbue onto an `ostream`;</span></div>
<div class="line"><a id="l00029" name="l00029"></a><span class="lineno">   29</span><span class="comment"> * but even within our own internal code the only public API used is beautified_locale(), which</span></div>
<div class="line"><a id="l00030" name="l00030"></a><span class="lineno">   30</span><span class="comment"> * returns a reference to a ready-made such `std::locale`.</span></div>
<div class="line"><a id="l00031" name="l00031"></a><span class="lineno">   31</span><span class="comment"> *</span></div>
<div class="line"><a id="l00032" name="l00032"></a><span class="lineno">   32</span><span class="comment"> * This facet enables the default `chrono` output behavior, except the &quot;micro&quot; short-form prefix</span></div>
<div class="line"><a id="l00033" name="l00033"></a><span class="lineno">   33</span><span class="comment"> * is just &quot;u&quot; instead of the default Unicode Greek letter mu.</span></div>
<div class="line"><a id="l00034" name="l00034"></a><span class="lineno">   34</span><span class="comment"> *</span></div>
<div class="line"><a id="l00035" name="l00035"></a><span class="lineno">   35</span><span class="comment"> * ### Implementation notes ###</span></div>
<div class="line"><a id="l00036" name="l00036"></a><span class="lineno">   36</span><span class="comment"> * How it does this is fairly self-explanatory, but finding out how to do it was annoyingly tricky due to the</span></div>
<div class="line"><a id="l00037" name="l00037"></a><span class="lineno">   37</span><span class="comment"> * inconsistent/outdated boost.chrono docs which only partially explain boost.chrono I/O v2.  Ultimately I had to</span></div>
<div class="line"><a id="l00038" name="l00038"></a><span class="lineno">   38</span><span class="comment"> * find the actual example `french.cpp` (not its outdated v1 version directly inside the main doc text, in Boost 1.76);</span></div>
<div class="line"><a id="l00039" name="l00039"></a><span class="lineno">   39</span><span class="comment"> * then cross-reference it with the Reference section that described the `duration_units_default` class.</span></div>
<div class="line"><a id="l00040" name="l00040"></a><span class="lineno">   40</span><span class="comment"> */</span></div>
<div class="line"><a id="l00041" name="l00041"></a><span class="lineno"><a class="line" href="classflow_1_1util_1_1Duration__units__beautified.html">   41</a></span><span class="keyword">class </span><a class="code hl_class" href="classflow_1_1util_1_1Duration__units__beautified.html">Duration_units_beautified</a> : <span class="keyword">public</span> <a class="code hl_class" href="classboost_1_1chrono_1_1duration__units__default.html">boost::chrono::duration_units_default</a>&lt;char&gt;</div>
<div class="line"><a id="l00042" name="l00042"></a><span class="lineno">   42</span>{</div>
<div class="line"><a id="l00043" name="l00043"></a><span class="lineno">   43</span><span class="keyword">public</span>:</div>
<div class="line"><a id="l00044" name="l00044"></a><span class="lineno">   44</span>  <span class="comment">// Methods.</span></div>
<div class="line"><a id="l00045" name="l00045"></a><span class="lineno">   45</span><span class="comment"></span> </div>
<div class="line"><a id="l00046" name="l00046"></a><span class="lineno">   46</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00047" name="l00047"></a><span class="lineno">   47</span><span class="comment">   * Returns a reference to a locale that -- if imbued onto an `ostream` --</span></div>
<div class="line"><a id="l00048" name="l00048"></a><span class="lineno">   48</span><span class="comment">   * equals `std::locale::classic` except beautified by a Duration_units_beautified facet (as described in</span></div>
<div class="line"><a id="l00049" name="l00049"></a><span class="lineno">   49</span><span class="comment">   * the class doc header).</span></div>
<div class="line"><a id="l00050" name="l00050"></a><span class="lineno">   50</span><span class="comment">   *</span></div>
<div class="line"><a id="l00051" name="l00051"></a><span class="lineno">   51</span><span class="comment">   * ### Thread safety and perf ###</span></div>
<div class="line"><a id="l00052" name="l00052"></a><span class="lineno">   52</span><span class="comment">   * This (`static`) method is safe to call concurrently with itself.  Internally it achieves this possibly by using a</span></div>
<div class="line"><a id="l00053" name="l00053"></a><span class="lineno">   53</span><span class="comment">   * simple mutex.  Since it is not expected one would call this frequently, let alone frequently enough for any</span></div>
<div class="line"><a id="l00054" name="l00054"></a><span class="lineno">   54</span><span class="comment">   * contention to occur, we consider this acceptable.</span></div>
<div class="line"><a id="l00055" name="l00055"></a><span class="lineno">   55</span><span class="comment">   *</span></div>
<div class="line"><a id="l00056" name="l00056"></a><span class="lineno">   56</span><span class="comment">   * @return See above.</span></div>
<div class="line"><a id="l00057" name="l00057"></a><span class="lineno">   57</span><span class="comment">   */</span></div>
<div class="line"><a id="l00058" name="l00058"></a><span class="lineno">   58</span>  <span class="keyword">static</span> <span class="keyword">const</span> std::locale&amp; <a class="code hl_function" href="classflow_1_1util_1_1Duration__units__beautified.html#aa689f853f75e06263d6875ae5824a4c6">beautified_locale</a>();</div>
<div class="line"><a id="l00059" name="l00059"></a><span class="lineno">   59</span><span class="comment"></span> </div>
<div class="line"><a id="l00060" name="l00060"></a><span class="lineno">   60</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00061" name="l00061"></a><span class="lineno">   61</span><span class="comment">   * Returns the prefix string for micro-units; namely the default thing for long-form format (&quot;micro&quot;) but</span></div>
<div class="line"><a id="l00062" name="l00062"></a><span class="lineno">   62</span><span class="comment">   * the non-default &quot;u&quot; for the short-form.  Hence microseconds are either &quot;microsecond[s]&quot; or &quot;us.&quot;</span></div>
<div class="line"><a id="l00063" name="l00063"></a><span class="lineno">   63</span><span class="comment">   *</span></div>
<div class="line"><a id="l00064" name="l00064"></a><span class="lineno">   64</span><span class="comment">   * ### Rationale ###</span></div>
<div class="line"><a id="l00065" name="l00065"></a><span class="lineno">   65</span><span class="comment">   * This is `public` only so as to work as a `virtual` facet interface element invoked by STL `ostream` machinery upon</span></div>
<div class="line"><a id="l00066" name="l00066"></a><span class="lineno">   66</span><span class="comment">   * imbuing `*this` onto a `locale`.  Since Duration_units_beautified is not exposed as a flow::util public API,</span></div>
<div class="line"><a id="l00067" name="l00067"></a><span class="lineno">   67</span><span class="comment">   * leaving this method `public` (to our internal code in this .cpp file only) is acceptable.</span></div>
<div class="line"><a id="l00068" name="l00068"></a><span class="lineno">   68</span><span class="comment">   *</span></div>
<div class="line"><a id="l00069" name="l00069"></a><span class="lineno">   69</span><span class="comment">   * @param style</span></div>
<div class="line"><a id="l00070" name="l00070"></a><span class="lineno">   70</span><span class="comment">   *        Either `name_format` or `symbol_format` (the latter being the short-form choice).</span></div>
<div class="line"><a id="l00071" name="l00071"></a><span class="lineno">   71</span><span class="comment">   * @param period_tag</span></div>
<div class="line"><a id="l00072" name="l00072"></a><span class="lineno">   72</span><span class="comment">   *        Tag indicating this method is for the micro prefix.</span></div>
<div class="line"><a id="l00073" name="l00073"></a><span class="lineno">   73</span><span class="comment">   * @return The prefix string.</span></div>
<div class="line"><a id="l00074" name="l00074"></a><span class="lineno">   74</span><span class="comment">   */</span></div>
<div class="line"><a id="l00075" name="l00075"></a><span class="lineno">   75</span>  <span class="keyword">typename</span> boost::chrono::duration_units&lt;char_type&gt;::string_type</div>
<div class="line"><a id="l00076" name="l00076"></a><span class="lineno">   76</span>    <a class="code hl_function" href="classflow_1_1util_1_1Duration__units__beautified.html#a278ff65fd0d9da3051d952557e4f9e46">do_get_ratio_prefix</a>(boost::chrono::duration_style style, boost::micro period_tag) <span class="keyword">const override</span>;</div>
<div class="line"><a id="l00077" name="l00077"></a><span class="lineno">   77</span> </div>
<div class="line"><a id="l00078" name="l00078"></a><span class="lineno">   78</span><span class="keyword">private</span>:</div>
<div class="line"><a id="l00079" name="l00079"></a><span class="lineno">   79</span>  <span class="comment">// Types.</span></div>
<div class="line"><a id="l00080" name="l00080"></a><span class="lineno">   80</span><span class="comment"></span> </div>
<div class="line"><a id="l00081" name="l00081"></a><span class="lineno">   81</span><span class="comment">  /// Short-hand for superclass.</span></div>
<div class="line"><a id="l00082" name="l00082"></a><span class="lineno"><a class="line" href="classflow_1_1util_1_1Duration__units__beautified.html#a680e64f096ccdad42b4f4c404d412391">   82</a></span><span class="comment"></span>  <span class="keyword">using </span><a class="code hl_class" href="classboost_1_1chrono_1_1duration__units__default.html">Duration_units_default</a> = <a class="code hl_class" href="classboost_1_1chrono_1_1duration__units__default.html">boost::chrono::duration_units_default&lt;char&gt;</a>;</div>
<div class="line"><a id="l00083" name="l00083"></a><span class="lineno">   83</span> </div>
<div class="line"><a id="l00084" name="l00084"></a><span class="lineno">   84</span>  <span class="comment">// Constructors/destructor.</span></div>
<div class="line"><a id="l00085" name="l00085"></a><span class="lineno">   85</span><span class="comment"></span> </div>
<div class="line"><a id="l00086" name="l00086"></a><span class="lineno">   86</span><span class="comment">  /// Constructs.</span></div>
<div class="line"><a id="l00087" name="l00087"></a><span class="lineno">   87</span><span class="comment"></span>  <span class="keyword">explicit</span> <a class="code hl_function" href="classflow_1_1util_1_1Duration__units__beautified.html#a1fe87e2f94792415055398097e6d494b">Duration_units_beautified</a>();</div>
<div class="line"><a id="l00088" name="l00088"></a><span class="lineno">   88</span> </div>
<div class="line"><a id="l00089" name="l00089"></a><span class="lineno">   89</span>  <span class="comment">// Data.</span></div>
<div class="line"><a id="l00090" name="l00090"></a><span class="lineno">   90</span><span class="comment"></span> </div>
<div class="line"><a id="l00091" name="l00091"></a><span class="lineno">   91</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00092" name="l00092"></a><span class="lineno">   92</span><span class="comment">   * Pointer returned by beautified_locale(), pointing to an object allocated exactly once; or null if that has not yet</span></div>
<div class="line"><a id="l00093" name="l00093"></a><span class="lineno">   93</span><span class="comment">   * been called.  The allocated object lives until the process exits.</span></div>
<div class="line"><a id="l00094" name="l00094"></a><span class="lineno">   94</span><span class="comment">   */</span></div>
<div class="line"><a id="l00095" name="l00095"></a><span class="lineno"><a class="line" href="classflow_1_1util_1_1Duration__units__beautified.html#a5c21a947d16a428314a077528876bde3">   95</a></span>  <span class="keyword">static</span> std::locale <span class="keyword">const</span> * <a class="code hl_variable" href="classflow_1_1util_1_1Duration__units__beautified.html#a5c21a947d16a428314a077528876bde3">s_beautified_locale_or_null</a>;</div>
<div class="line"><a id="l00096" name="l00096"></a><span class="lineno">   96</span><span class="comment"></span> </div>
<div class="line"><a id="l00097" name="l00097"></a><span class="lineno">   97</span><span class="comment">  /// Helper to initialize #s_beautified_locale_or_null at most once.</span></div>
<div class="line"><a id="l00098" name="l00098"></a><span class="lineno"><a class="line" href="classflow_1_1util_1_1Duration__units__beautified.html#aabd0fb641c4234515bac298d7a11d7c3">   98</a></span><span class="comment"></span>  <span class="keyword">static</span> boost::once_flag <a class="code hl_variable" href="classflow_1_1util_1_1Duration__units__beautified.html#aabd0fb641c4234515bac298d7a11d7c3">s_beautified_locale_init_flag</a>;</div>
<div class="line"><a id="l00099" name="l00099"></a><span class="lineno">   99</span>}; <span class="comment">// class Duration_units_beautified</span></div>
<div class="line"><a id="l00100" name="l00100"></a><span class="lineno">  100</span> </div>
<div class="line"><a id="l00101" name="l00101"></a><span class="lineno">  101</span><span class="comment">// Static initializers.</span></div>
<div class="line"><a id="l00102" name="l00102"></a><span class="lineno">  102</span> </div>
<div class="line"><a id="l00103" name="l00103"></a><span class="lineno">  103</span>std::locale <span class="keyword">const</span> * <a class="code hl_variable" href="classflow_1_1util_1_1Duration__units__beautified.html#a5c21a947d16a428314a077528876bde3">Duration_units_beautified::s_beautified_locale_or_null</a>(0);</div>
<div class="line"><a id="l00104" name="l00104"></a><span class="lineno">  104</span>boost::once_flag <a class="code hl_variable" href="classflow_1_1util_1_1Duration__units__beautified.html#aabd0fb641c4234515bac298d7a11d7c3">Duration_units_beautified::s_beautified_locale_init_flag</a>;</div>
<div class="line"><a id="l00105" name="l00105"></a><span class="lineno">  105</span> </div>
<div class="line"><a id="l00106" name="l00106"></a><span class="lineno">  106</span><span class="comment">// Implementations.</span></div>
<div class="line"><a id="l00107" name="l00107"></a><span class="lineno">  107</span> </div>
<div class="line"><a id="l00108" name="l00108"></a><span class="lineno">  108</span><span class="comment">// Local class implementations.</span></div>
<div class="line"><a id="l00109" name="l00109"></a><span class="lineno">  109</span> </div>
<div class="line"><a id="l00110" name="l00110"></a><span class="lineno"><a class="line" href="classflow_1_1util_1_1Duration__units__beautified.html#a1fe87e2f94792415055398097e6d494b">  110</a></span><a class="code hl_function" href="classflow_1_1util_1_1Duration__units__beautified.html#a1fe87e2f94792415055398097e6d494b">Duration_units_beautified::Duration_units_beautified</a>() :</div>
<div class="line"><a id="l00111" name="l00111"></a><span class="lineno">  111</span>  <a class="code hl_class" href="classboost_1_1chrono_1_1duration__units__default.html">Duration_units_default</a>(0) <span class="comment">// Just use `refs == 0`.  See boost::chrono docs, if you care to know more re. this detail.</span></div>
<div class="line"><a id="l00112" name="l00112"></a><span class="lineno">  112</span>{</div>
<div class="line"><a id="l00113" name="l00113"></a><span class="lineno">  113</span>  <span class="comment">// That&#39;s all.</span></div>
<div class="line"><a id="l00114" name="l00114"></a><span class="lineno">  114</span>}</div>
<div class="line"><a id="l00115" name="l00115"></a><span class="lineno">  115</span> </div>
<div class="line"><a id="l00116" name="l00116"></a><span class="lineno"><a class="line" href="classflow_1_1util_1_1Duration__units__beautified.html#aa689f853f75e06263d6875ae5824a4c6">  116</a></span><span class="keyword">const</span> std::locale&amp; <a class="code hl_function" href="classflow_1_1util_1_1Duration__units__beautified.html#aa689f853f75e06263d6875ae5824a4c6">Duration_units_beautified::beautified_locale</a>() <span class="comment">// Static.</span></div>
<div class="line"><a id="l00117" name="l00117"></a><span class="lineno">  117</span>{</div>
<div class="line"><a id="l00118" name="l00118"></a><span class="lineno">  118</span>  <span class="keyword">using </span>boost::call_once;</div>
<div class="line"><a id="l00119" name="l00119"></a><span class="lineno">  119</span>  <span class="keyword">using </span>std::locale;</div>
<div class="line"><a id="l00120" name="l00120"></a><span class="lineno">  120</span> </div>
<div class="line"><a id="l00121" name="l00121"></a><span class="lineno">  121</span>  <span class="comment">// As advertised create (thread-safely) a locale that survives until the process exits.</span></div>
<div class="line"><a id="l00122" name="l00122"></a><span class="lineno">  122</span>  call_once(<a class="code hl_variable" href="classflow_1_1util_1_1Duration__units__beautified.html#aabd0fb641c4234515bac298d7a11d7c3">s_beautified_locale_init_flag</a>,</div>
<div class="line"><a id="l00123" name="l00123"></a><span class="lineno">  123</span>            [&amp;]() { <a class="code hl_variable" href="classflow_1_1util_1_1Duration__units__beautified.html#a5c21a947d16a428314a077528876bde3">s_beautified_locale_or_null</a> = <span class="keyword">new</span> locale(locale::classic(), <span class="keyword">new</span> <a class="code hl_class" href="classflow_1_1util_1_1Duration__units__beautified.html">Duration_units_beautified</a>); });</div>
<div class="line"><a id="l00124" name="l00124"></a><span class="lineno">  124</span> </div>
<div class="line"><a id="l00125" name="l00125"></a><span class="lineno">  125</span>  assert(<a class="code hl_variable" href="classflow_1_1util_1_1Duration__units__beautified.html#a5c21a947d16a428314a077528876bde3">s_beautified_locale_or_null</a>);</div>
<div class="line"><a id="l00126" name="l00126"></a><span class="lineno">  126</span>  <span class="keywordflow">return</span> *<a class="code hl_variable" href="classflow_1_1util_1_1Duration__units__beautified.html#a5c21a947d16a428314a077528876bde3">s_beautified_locale_or_null</a>;</div>
<div class="line"><a id="l00127" name="l00127"></a><span class="lineno">  127</span>}</div>
<div class="line"><a id="l00128" name="l00128"></a><span class="lineno">  128</span> </div>
<div class="line"><a id="l00129" name="l00129"></a><span class="lineno"><a class="line" href="classflow_1_1util_1_1Duration__units__beautified.html#a278ff65fd0d9da3051d952557e4f9e46">  129</a></span>boost::chrono::duration_units&lt;char&gt;::string_type <a class="code hl_function" href="classflow_1_1util_1_1Duration__units__beautified.html#a278ff65fd0d9da3051d952557e4f9e46">Duration_units_beautified::do_get_ratio_prefix</a></div>
<div class="line"><a id="l00130" name="l00130"></a><span class="lineno">  130</span>                                                   (boost::chrono::duration_style style,</div>
<div class="line"><a id="l00131" name="l00131"></a><span class="lineno">  131</span>                                                    boost::micro period_tag) <span class="keyword">const</span> <span class="comment">// Virtual.</span></div>
<div class="line"><a id="l00132" name="l00132"></a><span class="lineno">  132</span>{</div>
<div class="line"><a id="l00133" name="l00133"></a><span class="lineno">  133</span>  <span class="comment">// See Implementation in our class doc header for background.</span></div>
<div class="line"><a id="l00134" name="l00134"></a><span class="lineno">  134</span> </div>
<div class="line"><a id="l00135" name="l00135"></a><span class="lineno">  135</span>  <span class="keywordflow">if</span> (style == boost::chrono::duration_style::symbol)</div>
<div class="line"><a id="l00136" name="l00136"></a><span class="lineno">  136</span>  {</div>
<div class="line"><a id="l00137" name="l00137"></a><span class="lineno">  137</span>    <span class="keywordflow">return</span> <span class="stringliteral">&quot;u&quot;</span>; <span class="comment">// Normally this would be the Unicode string for the Greek letter mu, but we hate that stuff.</span></div>
<div class="line"><a id="l00138" name="l00138"></a><span class="lineno">  138</span>  }</div>
<div class="line"><a id="l00139" name="l00139"></a><span class="lineno">  139</span>  <span class="comment">// else</span></div>
<div class="line"><a id="l00140" name="l00140"></a><span class="lineno">  140</span>  <span class="keywordflow">return</span> Duration_units_default::do_get_ratio_prefix(style, period_tag);</div>
<div class="line"><a id="l00141" name="l00141"></a><span class="lineno">  141</span>}</div>
<div class="line"><a id="l00142" name="l00142"></a><span class="lineno">  142</span> </div>
<div class="line"><a id="l00143" name="l00143"></a><span class="lineno">  143</span><span class="comment">// Free function implementations.</span></div>
<div class="line"><a id="l00144" name="l00144"></a><span class="lineno">  144</span> </div>
<div class="line"><a id="l00145" name="l00145"></a><span class="lineno">  145</span><a class="code hl_function" href="classflow_1_1util_1_1Null__interface.html#a5916282577627e424a09884347eddbba">Null_interface::~Null_interface</a>() = <span class="keywordflow">default</span>;</div>
<div class="line"><a id="l00146" name="l00146"></a><span class="lineno">  146</span> </div>
<div class="line"><a id="l00147" name="l00147"></a><span class="lineno"><a class="line" href="namespaceflow_1_1util.html#ad92ad411feccf73908abe6ed130d48f5">  147</a></span>boost::chrono::microseconds <a class="code hl_function" href="namespaceflow_1_1util.html#ad92ad411feccf73908abe6ed130d48f5">time_since_posix_epoch</a>()</div>
<div class="line"><a id="l00148" name="l00148"></a><span class="lineno">  148</span>{</div>
<div class="line"><a id="l00149" name="l00149"></a><span class="lineno">  149</span>  <span class="comment">/* Get the # of microseconds since the advertised Epoch time point, which is explicitly what microsec_clock</span></div>
<div class="line"><a id="l00150" name="l00150"></a><span class="lineno">  150</span><span class="comment">   * gives us, the latter being officially the most precise documented clock in boost.date_time.  Then just</span></div>
<div class="line"><a id="l00151" name="l00151"></a><span class="lineno">  151</span><span class="comment">   * make a boost.chrono duration&lt;&gt; out of that. */</span></div>
<div class="line"><a id="l00152" name="l00152"></a><span class="lineno">  152</span>  <span class="keyword">using </span>boost::posix_time::microsec_clock;</div>
<div class="line"><a id="l00153" name="l00153"></a><span class="lineno">  153</span>  <span class="keyword">using </span>boost::posix_time::ptime;</div>
<div class="line"><a id="l00154" name="l00154"></a><span class="lineno">  154</span>  <span class="keyword">using </span>boost::chrono::microseconds;</div>
<div class="line"><a id="l00155" name="l00155"></a><span class="lineno">  155</span>  <span class="keyword">using </span>boost::gregorian::date;</div>
<div class="line"><a id="l00156" name="l00156"></a><span class="lineno">  156</span>  <span class="keywordflow">return</span> microseconds((microsec_clock::universal_time() - ptime(date(1970, 1, 1)))</div>
<div class="line"><a id="l00157" name="l00157"></a><span class="lineno">  157</span>                      .total_microseconds());</div>
<div class="line"><a id="l00158" name="l00158"></a><span class="lineno">  158</span> </div>
<div class="line"><a id="l00159" name="l00159"></a><span class="lineno">  159</span>  <span class="comment">/* I am using boost.date_time machinery to get the UTC time and then the # of usec since the</span></div>
<div class="line"><a id="l00160" name="l00160"></a><span class="lineno">  160</span><span class="comment">   * exact epoch time point.  Beyond dealing with calendars and the like, I find boost.date_time</span></div>
<div class="line"><a id="l00161" name="l00161"></a><span class="lineno">  161</span><span class="comment">   * suspect and would always prefer boost.chrono, but my attempt to entirely use that for this</span></div>
<div class="line"><a id="l00162" name="l00162"></a><span class="lineno">  162</span><span class="comment">   * failed. chrono::system_clock::now() actually returns the current time point from the correct</span></div>
<div class="line"><a id="l00163" name="l00163"></a><span class="lineno">  163</span><span class="comment">   * clock, with the best possible resolution.  That&#39;s great, but then the docs say that the epoch</span></div>
<div class="line"><a id="l00164" name="l00164"></a><span class="lineno">  164</span><span class="comment">   * against which this is computed is not defined and to use system_clock::to_time_t() to</span></div>
<div class="line"><a id="l00165" name="l00165"></a><span class="lineno">  165</span><span class="comment">   * convert now() to a count since the actual POSIX Epoch.  Again, that&#39;s great, except that</span></div>
<div class="line"><a id="l00166" name="l00166"></a><span class="lineno">  166</span><span class="comment">   * time_t is in seconds, which means the juicy as-high-res-as-possible time point is rounded</span></div>
<div class="line"><a id="l00167" name="l00167"></a><span class="lineno">  167</span><span class="comment">   * to seconds, destroying information irretrievably.  We need more resolution than seconds, so</span></div>
<div class="line"><a id="l00168" name="l00168"></a><span class="lineno">  168</span><span class="comment">   * we&#39;ve no choice but to rely on the crusty boost.date_time wall clock time.</span></div>
<div class="line"><a id="l00169" name="l00169"></a><span class="lineno">  169</span><span class="comment">   *</span></div>
<div class="line"><a id="l00170" name="l00170"></a><span class="lineno">  170</span><span class="comment">   * It doesn&#39;t matter that much... it&#39;s just style in this one little function. */</span></div>
<div class="line"><a id="l00171" name="l00171"></a><span class="lineno">  171</span>}</div>
<div class="line"><a id="l00172" name="l00172"></a><span class="lineno">  172</span> </div>
<div class="line"><a id="l00173" name="l00173"></a><span class="lineno"><a class="line" href="namespaceflow_1_1util.html#a0955a29930075ac1fe393896c089b911">  173</a></span><span class="keywordtype">void</span> <a class="code hl_function" href="namespaceflow_1_1util.html#a0955a29930075ac1fe393896c089b911">beautify_chrono_ostream</a>(std::ostream* os_ptr)</div>
<div class="line"><a id="l00174" name="l00174"></a><span class="lineno">  174</span>{</div>
<div class="line"><a id="l00175" name="l00175"></a><span class="lineno">  175</span>  <span class="keyword">using </span>boost::chrono::symbol_format;</div>
<div class="line"><a id="l00176" name="l00176"></a><span class="lineno">  176</span> </div>
<div class="line"><a id="l00177" name="l00177"></a><span class="lineno">  177</span>  <span class="keyword">auto</span>&amp; os = *os_ptr;</div>
<div class="line"><a id="l00178" name="l00178"></a><span class="lineno">  178</span> </div>
<div class="line"><a id="l00179" name="l00179"></a><span class="lineno">  179</span>  <span class="comment">/* We prefer all output of durations to be like &quot;ms&quot; and not &quot;milliseconds.&quot;</span></div>
<div class="line"><a id="l00180" name="l00180"></a><span class="lineno">  180</span><span class="comment">   * Also we hate the Unicode Greek mu prefix for micro, so we use custom facet to have something nicer. */</span></div>
<div class="line"><a id="l00181" name="l00181"></a><span class="lineno">  181</span> </div>
<div class="line"><a id="l00182" name="l00182"></a><span class="lineno">  182</span>  os.imbue(<a class="code hl_function" href="classflow_1_1util_1_1Duration__units__beautified.html#aa689f853f75e06263d6875ae5824a4c6">Duration_units_beautified::beautified_locale</a>());</div>
<div class="line"><a id="l00183" name="l00183"></a><span class="lineno">  183</span>  os &lt;&lt; symbol_format;</div>
<div class="line"><a id="l00184" name="l00184"></a><span class="lineno">  184</span>}</div>
<div class="line"><a id="l00185" name="l00185"></a><span class="lineno">  185</span> </div>
<div class="line"><a id="l00186" name="l00186"></a><span class="lineno"><a class="line" href="namespaceflow_1_1util.html#a418b56a178c07100eef78da5c9d6ee7a">  186</a></span><span class="keywordtype">size_t</span> <a class="code hl_function" href="namespaceflow_1_1util.html#a418b56a178c07100eef78da5c9d6ee7a">deep_size</a>(<span class="keyword">const</span> std::string&amp; val)</div>
<div class="line"><a id="l00187" name="l00187"></a><span class="lineno">  187</span>{</div>
<div class="line"><a id="l00188" name="l00188"></a><span class="lineno">  188</span>  <span class="comment">// We&#39;re following the loose pattern explained at the end of Async_file_logger::mem_cost().</span></div>
<div class="line"><a id="l00189" name="l00189"></a><span class="lineno">  189</span> </div>
<div class="line"><a id="l00190" name="l00190"></a><span class="lineno">  190</span><span class="preprocessor">#if (!defined(__GNUC__)) || (!defined(__x86_64__))</span></div>
<div class="line"><a id="l00191" name="l00191"></a><span class="lineno">  191</span>  <span class="keyword">static_assert</span>(<span class="keyword">false</span>, <span class="stringliteral">&quot;An estimation trick below has only been checked with x64 gcc and clang.  &quot;</span></div>
<div class="line"><a id="l00192" name="l00192"></a><span class="lineno">  192</span>                         <span class="stringliteral">&quot;Revisit code for other envs.&quot;</span>);</div>
<div class="line"><a id="l00193" name="l00193"></a><span class="lineno">  193</span><span class="preprocessor">#endif</span></div>
<div class="line"><a id="l00194" name="l00194"></a><span class="lineno">  194</span> </div>
<div class="line"><a id="l00195" name="l00195"></a><span class="lineno">  195</span>  <span class="comment">/* If it is long enough to not fit inside the std::string object itself</span></div>
<div class="line"><a id="l00196" name="l00196"></a><span class="lineno">  196</span><span class="comment">   * (common optimization in STL: Small String Optimization), then it&#39;ll allocate a buffer in heap.</span></div>
<div class="line"><a id="l00197" name="l00197"></a><span class="lineno">  197</span><span class="comment">   * We could even determine whether it actually happened here at runtime, but that wastes cycles</span></div>
<div class="line"><a id="l00198" name="l00198"></a><span class="lineno">  198</span><span class="comment">   * (original use case is in log::Async_file_logger specifically where every cycle counts).</span></div>
<div class="line"><a id="l00199" name="l00199"></a><span class="lineno">  199</span><span class="comment">   * Instead we&#39;ve established experimentally that with default STL and clangs 4-17 and gccs 5-13</span></div>
<div class="line"><a id="l00200" name="l00200"></a><span class="lineno">  200</span><span class="comment">   * SSO is active for .capacity() &lt;= 15.  @todo Check LLVM libc++ too.  Prob same thing... SSO is well established. */</span></div>
<div class="line"><a id="l00201" name="l00201"></a><span class="lineno">  201</span>  <span class="keyword">const</span> <span class="keyword">auto</span> sz = val.capacity();</div>
<div class="line"><a id="l00202" name="l00202"></a><span class="lineno">  202</span>  <span class="keywordflow">return</span> (sz &lt;= 15) ? 0 : sz;</div>
<div class="line"><a id="l00203" name="l00203"></a><span class="lineno">  203</span>}</div>
<div class="line"><a id="l00204" name="l00204"></a><span class="lineno">  204</span> </div>
<div class="line"><a id="l00205" name="l00205"></a><span class="lineno">  205</span>} <span class="comment">// namespace flow::util</span></div>
<div class="ttc" id="aclassboost_1_1chrono_1_1duration__units__default_html"><div class="ttname"><a href="classboost_1_1chrono_1_1duration__units__default.html">boost::chrono::duration_units_default</a></div></div>
<div class="ttc" id="aclassflow_1_1util_1_1Duration__units__beautified_html"><div class="ttname"><a href="classflow_1_1util_1_1Duration__units__beautified.html">flow::util::Duration_units_beautified</a></div><div class="ttdoc">Internally used class that enables some of the activities of beautify_chrono_ostream() API.</div><div class="ttdef"><b>Definition:</b> <a href="util_8cpp_source.html#l00041">util.cpp:42</a></div></div>
<div class="ttc" id="aclassflow_1_1util_1_1Duration__units__beautified_html_a1fe87e2f94792415055398097e6d494b"><div class="ttname"><a href="classflow_1_1util_1_1Duration__units__beautified.html#a1fe87e2f94792415055398097e6d494b">flow::util::Duration_units_beautified::Duration_units_beautified</a></div><div class="ttdeci">Duration_units_beautified()</div><div class="ttdoc">Constructs.</div><div class="ttdef"><b>Definition:</b> <a href="util_8cpp_source.html#l00110">util.cpp:110</a></div></div>
<div class="ttc" id="aclassflow_1_1util_1_1Duration__units__beautified_html_a278ff65fd0d9da3051d952557e4f9e46"><div class="ttname"><a href="classflow_1_1util_1_1Duration__units__beautified.html#a278ff65fd0d9da3051d952557e4f9e46">flow::util::Duration_units_beautified::do_get_ratio_prefix</a></div><div class="ttdeci">boost::chrono::duration_units&lt; char_type &gt;::string_type do_get_ratio_prefix(boost::chrono::duration_style style, boost::micro period_tag) const override</div><div class="ttdoc">Returns the prefix string for micro-units; namely the default thing for long-form format (&quot;micro&quot;) bu...</div><div class="ttdef"><b>Definition:</b> <a href="util_8cpp_source.html#l00129">util.cpp:130</a></div></div>
<div class="ttc" id="aclassflow_1_1util_1_1Duration__units__beautified_html_a5c21a947d16a428314a077528876bde3"><div class="ttname"><a href="classflow_1_1util_1_1Duration__units__beautified.html#a5c21a947d16a428314a077528876bde3">flow::util::Duration_units_beautified::s_beautified_locale_or_null</a></div><div class="ttdeci">static std::locale const  * s_beautified_locale_or_null</div><div class="ttdoc">Pointer returned by beautified_locale(), pointing to an object allocated exactly once; or null if tha...</div><div class="ttdef"><b>Definition:</b> <a href="util_8cpp_source.html#l00095">util.cpp:95</a></div></div>
<div class="ttc" id="aclassflow_1_1util_1_1Duration__units__beautified_html_aa689f853f75e06263d6875ae5824a4c6"><div class="ttname"><a href="classflow_1_1util_1_1Duration__units__beautified.html#aa689f853f75e06263d6875ae5824a4c6">flow::util::Duration_units_beautified::beautified_locale</a></div><div class="ttdeci">static const std::locale &amp; beautified_locale()</div><div class="ttdoc">Returns a reference to a locale that – if imbued onto an ostream – equals std::locale::classic except...</div><div class="ttdef"><b>Definition:</b> <a href="util_8cpp_source.html#l00116">util.cpp:116</a></div></div>
<div class="ttc" id="aclassflow_1_1util_1_1Duration__units__beautified_html_aabd0fb641c4234515bac298d7a11d7c3"><div class="ttname"><a href="classflow_1_1util_1_1Duration__units__beautified.html#aabd0fb641c4234515bac298d7a11d7c3">flow::util::Duration_units_beautified::s_beautified_locale_init_flag</a></div><div class="ttdeci">static boost::once_flag s_beautified_locale_init_flag</div><div class="ttdoc">Helper to initialize s_beautified_locale_or_null at most once.</div><div class="ttdef"><b>Definition:</b> <a href="util_8cpp_source.html#l00098">util.cpp:98</a></div></div>
<div class="ttc" id="aclassflow_1_1util_1_1Null__interface_html_a5916282577627e424a09884347eddbba"><div class="ttname"><a href="classflow_1_1util_1_1Null__interface.html#a5916282577627e424a09884347eddbba">flow::util::Null_interface::~Null_interface</a></div><div class="ttdeci">virtual ~Null_interface()=0</div><div class="ttdoc">Boring virtual destructor.</div></div>
<div class="ttc" id="anamespaceflow_1_1util_html"><div class="ttname"><a href="namespaceflow_1_1util.html">flow::util</a></div><div class="ttdoc">Flow module containing miscellaneous general-use facilities that don't fit into any other Flow module...</div><div class="ttdef"><b>Definition:</b> <a href="basic__blob_8hpp_source.html#l00028">basic_blob.hpp:29</a></div></div>
<div class="ttc" id="anamespaceflow_1_1util_html_a0955a29930075ac1fe393896c089b911"><div class="ttname"><a href="namespaceflow_1_1util.html#a0955a29930075ac1fe393896c089b911">flow::util::beautify_chrono_ostream</a></div><div class="ttdeci">void beautify_chrono_ostream(std::ostream *os_ptr)</div><div class="ttdoc">Sets certain chrono-related formatting on the given ostream that results in a consistent,...</div><div class="ttdef"><b>Definition:</b> <a href="util_8cpp_source.html#l00173">util.cpp:173</a></div></div>
<div class="ttc" id="anamespaceflow_1_1util_html_a418b56a178c07100eef78da5c9d6ee7a"><div class="ttname"><a href="namespaceflow_1_1util.html#a418b56a178c07100eef78da5c9d6ee7a">flow::util::deep_size</a></div><div class="ttdeci">size_t deep_size(const std::string &amp;val)</div><div class="ttdoc">Estimate of memory footprint of the given value, including memory allocated on its behalf – but exclu...</div><div class="ttdef"><b>Definition:</b> <a href="util_8cpp_source.html#l00186">util.cpp:186</a></div></div>
<div class="ttc" id="anamespaceflow_1_1util_html_ad92ad411feccf73908abe6ed130d48f5"><div class="ttname"><a href="namespaceflow_1_1util.html#ad92ad411feccf73908abe6ed130d48f5">flow::util::time_since_posix_epoch</a></div><div class="ttdeci">boost::chrono::microseconds time_since_posix_epoch()</div><div class="ttdoc">Get the current POSIX (Unix) time as a duration from the Epoch time point.</div><div class="ttdef"><b>Definition:</b> <a href="util_8cpp_source.html#l00147">util.cpp:147</a></div></div>
<div class="ttc" id="autil_2util_8hpp_html"><div class="ttname"><a href="util_2util_8hpp.html">util.hpp</a></div></div>
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